linux/drivers/acpi/video_detect.c
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   1/*
   2 *  Copyright (C) 2008       SuSE Linux Products GmbH
   3 *                           Thomas Renninger <trenn@suse.de>
   4 *
   5 *  May be copied or modified under the terms of the GNU General Public License
   6 *
   7 * video_detect.c:
   8 * Provides acpi_is_video_device() for early scanning of ACPI devices in scan.c
   9 * There a Linux specific (Spec does not provide a HID for video devices) is
  10 * assigned
  11 *
  12 * After PCI devices are glued with ACPI devices
  13 * acpi_get_pci_dev() can be called to identify ACPI graphics
  14 * devices for which a real graphics card is plugged in
  15 *
  16 * Now acpi_video_get_capabilities() can be called to check which
  17 * capabilities the graphics cards plugged in support. The check for general
  18 * video capabilities will be triggered by the first caller of
  19 * acpi_video_get_capabilities(NULL); which will happen when the first
  20 * backlight switching supporting driver calls:
  21 * acpi_video_backlight_support();
  22 *
  23 * Depending on whether ACPI graphics extensions (cmp. ACPI spec Appendix B)
  24 * are available, video.ko should be used to handle the device.
  25 *
  26 * Otherwise vendor specific drivers like thinkpad_acpi, asus-laptop,
  27 * sony_acpi,... can take care about backlight brightness.
  28 *
  29 * If CONFIG_ACPI_VIDEO is neither set as "compiled in" (y) nor as a module (m)
  30 * this file will not be compiled, acpi_video_get_capabilities() and
  31 * acpi_video_backlight_support() will always return 0 and vendor specific
  32 * drivers always can handle backlight.
  33 *
  34 */
  35
  36#include <linux/export.h>
  37#include <linux/acpi.h>
  38#include <linux/dmi.h>
  39#include <linux/pci.h>
  40
  41#define PREFIX "ACPI: "
  42
  43ACPI_MODULE_NAME("video");
  44#define _COMPONENT              ACPI_VIDEO_COMPONENT
  45
  46static long acpi_video_support;
  47static bool acpi_video_caps_checked;
  48
  49static acpi_status
  50acpi_backlight_cap_match(acpi_handle handle, u32 level, void *context,
  51                          void **retyurn_value)
  52{
  53        long *cap = context;
  54        acpi_handle h_dummy;
  55
  56        if (ACPI_SUCCESS(acpi_get_handle(handle, "_BCM", &h_dummy)) &&
  57            ACPI_SUCCESS(acpi_get_handle(handle, "_BCL", &h_dummy))) {
  58                ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found generic backlight "
  59                                  "support\n"));
  60                *cap |= ACPI_VIDEO_BACKLIGHT;
  61                if (ACPI_FAILURE(acpi_get_handle(handle, "_BQC", &h_dummy)))
  62                        printk(KERN_WARNING FW_BUG PREFIX "No _BQC method, "
  63                                "cannot determine initial brightness\n");
  64                /* We have backlight support, no need to scan further */
  65                return AE_CTRL_TERMINATE;
  66        }
  67        return 0;
  68}
  69
  70/* Returns true if the ACPI object is a video device which can be
  71 * handled by video.ko.
  72 * The device will get a Linux specific CID added in scan.c to
  73 * identify the device as an ACPI graphics device
  74 * Be aware that the graphics device may not be physically present
  75 * Use acpi_video_get_capabilities() to detect general ACPI video
  76 * capabilities of present cards
  77 */
  78long acpi_is_video_device(acpi_handle handle)
  79{
  80        acpi_handle h_dummy;
  81        long video_caps = 0;
  82
  83        /* Is this device able to support video switching ? */
  84        if (ACPI_SUCCESS(acpi_get_handle(handle, "_DOD", &h_dummy)) ||
  85            ACPI_SUCCESS(acpi_get_handle(handle, "_DOS", &h_dummy)))
  86                video_caps |= ACPI_VIDEO_OUTPUT_SWITCHING;
  87
  88        /* Is this device able to retrieve a video ROM ? */
  89        if (ACPI_SUCCESS(acpi_get_handle(handle, "_ROM", &h_dummy)))
  90                video_caps |= ACPI_VIDEO_ROM_AVAILABLE;
  91
  92        /* Is this device able to configure which video head to be POSTed ? */
  93        if (ACPI_SUCCESS(acpi_get_handle(handle, "_VPO", &h_dummy)) &&
  94            ACPI_SUCCESS(acpi_get_handle(handle, "_GPD", &h_dummy)) &&
  95            ACPI_SUCCESS(acpi_get_handle(handle, "_SPD", &h_dummy)))
  96                video_caps |= ACPI_VIDEO_DEVICE_POSTING;
  97
  98        /* Only check for backlight functionality if one of the above hit. */
  99        if (video_caps)
 100                acpi_walk_namespace(ACPI_TYPE_DEVICE, handle,
 101                                    ACPI_UINT32_MAX, acpi_backlight_cap_match, NULL,
 102                                    &video_caps, NULL);
 103
 104        return video_caps;
 105}
 106EXPORT_SYMBOL(acpi_is_video_device);
 107
 108static acpi_status
 109find_video(acpi_handle handle, u32 lvl, void *context, void **rv)
 110{
 111        long *cap = context;
 112        struct pci_dev *dev;
 113        struct acpi_device *acpi_dev;
 114
 115        const struct acpi_device_id video_ids[] = {
 116                {ACPI_VIDEO_HID, 0},
 117                {"", 0},
 118        };
 119        if (acpi_bus_get_device(handle, &acpi_dev))
 120                return AE_OK;
 121
 122        if (!acpi_match_device_ids(acpi_dev, video_ids)) {
 123                dev = acpi_get_pci_dev(handle);
 124                if (!dev)
 125                        return AE_OK;
 126                pci_dev_put(dev);
 127                *cap |= acpi_is_video_device(handle);
 128        }
 129        return AE_OK;
 130}
 131
 132/* Force to use vendor driver when the ACPI device is known to be
 133 * buggy */
 134static int video_detect_force_vendor(const struct dmi_system_id *d)
 135{
 136        acpi_video_support |= ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
 137        return 0;
 138}
 139
 140static struct dmi_system_id video_detect_dmi_table[] = {
 141        /* On Samsung X360, the BIOS will set a flag (VDRV) if generic
 142         * ACPI backlight device is used. This flag will definitively break
 143         * the backlight interface (even the vendor interface) untill next
 144         * reboot. It's why we should prevent video.ko from being used here
 145         * and we can't rely on a later call to acpi_video_unregister().
 146         */
 147        {
 148         .callback = video_detect_force_vendor,
 149         .ident = "X360",
 150         .matches = {
 151                DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
 152                DMI_MATCH(DMI_PRODUCT_NAME, "X360"),
 153                DMI_MATCH(DMI_BOARD_NAME, "X360"),
 154                },
 155        },
 156        {
 157        .callback = video_detect_force_vendor,
 158        .ident = "Asus UL30VT",
 159        .matches = {
 160                DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
 161                DMI_MATCH(DMI_PRODUCT_NAME, "UL30VT"),
 162                },
 163        },
 164        {
 165        .callback = video_detect_force_vendor,
 166        .ident = "Asus UL30A",
 167        .matches = {
 168                DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
 169                DMI_MATCH(DMI_PRODUCT_NAME, "UL30A"),
 170                },
 171        },
 172        { },
 173};
 174
 175/*
 176 * Returns the video capabilities of a specific ACPI graphics device
 177 *
 178 * if NULL is passed as argument all ACPI devices are enumerated and
 179 * all graphics capabilities of physically present devices are
 180 * summarized and returned. This is cached and done only once.
 181 */
 182long acpi_video_get_capabilities(acpi_handle graphics_handle)
 183{
 184        long caps = 0;
 185        struct acpi_device *tmp_dev;
 186        acpi_status status;
 187
 188        if (acpi_video_caps_checked && graphics_handle == NULL)
 189                return acpi_video_support;
 190
 191        if (!graphics_handle) {
 192                /* Only do the global walk through all graphics devices once */
 193                acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 194                                    ACPI_UINT32_MAX, find_video, NULL,
 195                                    &caps, NULL);
 196                /* There might be boot param flags set already... */
 197                acpi_video_support |= caps;
 198                acpi_video_caps_checked = 1;
 199                /* Add blacklists here. Be careful to use the right *DMI* bits
 200                 * to still be able to override logic via boot params, e.g.:
 201                 *
 202                 *   if (dmi_name_in_vendors("XY")) {
 203                 *      acpi_video_support |=
 204                 *              ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
 205                 *}
 206                 */
 207
 208                dmi_check_system(video_detect_dmi_table);
 209        } else {
 210                status = acpi_bus_get_device(graphics_handle, &tmp_dev);
 211                if (ACPI_FAILURE(status)) {
 212                        ACPI_EXCEPTION((AE_INFO, status, "Invalid device"));
 213                        return 0;
 214                }
 215                acpi_walk_namespace(ACPI_TYPE_DEVICE, graphics_handle,
 216                                    ACPI_UINT32_MAX, find_video, NULL,
 217                                    &caps, NULL);
 218        }
 219        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "We have 0x%lX video support %s %s\n",
 220                          graphics_handle ? caps : acpi_video_support,
 221                          graphics_handle ? "on device " : "in general",
 222                          graphics_handle ? acpi_device_bid(tmp_dev) : ""));
 223        return caps;
 224}
 225EXPORT_SYMBOL(acpi_video_get_capabilities);
 226
 227static void acpi_video_caps_check(void)
 228{
 229        /*
 230         * We must check whether the ACPI graphics device is physically plugged
 231         * in. Therefore this must be called after binding PCI and ACPI devices
 232         */
 233        if (!acpi_video_caps_checked)
 234                acpi_video_get_capabilities(NULL);
 235}
 236
 237/* Promote the vendor interface instead of the generic video module.
 238 * This function allow DMI blacklists to be implemented by externals
 239 * platform drivers instead of putting a big blacklist in video_detect.c
 240 * After calling this function you will probably want to call
 241 * acpi_video_unregister() to make sure the video module is not loaded
 242 */
 243void acpi_video_dmi_promote_vendor(void)
 244{
 245        acpi_video_caps_check();
 246        acpi_video_support |= ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
 247}
 248EXPORT_SYMBOL(acpi_video_dmi_promote_vendor);
 249
 250/* To be called when a driver who previously promoted the vendor
 251 * interface */
 252void acpi_video_dmi_demote_vendor(void)
 253{
 254        acpi_video_caps_check();
 255        acpi_video_support &= ~ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
 256}
 257EXPORT_SYMBOL(acpi_video_dmi_demote_vendor);
 258
 259/* Returns true if video.ko can do backlight switching */
 260int acpi_video_backlight_support(void)
 261{
 262        acpi_video_caps_check();
 263
 264        /* First check for boot param -> highest prio */
 265        if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR)
 266                return 0;
 267        else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO)
 268                return 1;
 269
 270        /* Then check for DMI blacklist -> second highest prio */
 271        if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VENDOR)
 272                return 0;
 273        else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VIDEO)
 274                return 1;
 275
 276        /* Then go the default way */
 277        return acpi_video_support & ACPI_VIDEO_BACKLIGHT;
 278}
 279EXPORT_SYMBOL(acpi_video_backlight_support);
 280
 281/*
 282 * Use acpi_backlight=vendor/video to force that backlight switching
 283 * is processed by vendor specific acpi drivers or video.ko driver.
 284 */
 285static int __init acpi_backlight(char *str)
 286{
 287        if (str == NULL || *str == '\0')
 288                return 1;
 289        else {
 290                if (!strcmp("vendor", str))
 291                        acpi_video_support |=
 292                                ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR;
 293                if (!strcmp("video", str))
 294                        acpi_video_support |=
 295                                ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO;
 296        }
 297        return 1;
 298}
 299__setup("acpi_backlight=", acpi_backlight);
 300
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